Subsequently, the system of three unbalanced phasors is converted to three symmetrical components, namely the positive, negative, and zero sequences. Then, the Chow-Liu algorithm is proved to be optimal for identifying the multi-phase topology by utilizing power flow equations and the conditional independence relationships implied by the radial multi-phase structure of distribution grids. As a highlight, the proposed method does not require PMUs and is robust to incorrect phase labels, which is a critical problem in distribution grid operations. This feature is due to the label-invariant property of mutual information. Another major contribution is bus phase correction and identification. Specifically, a data-driven approach is proposed to identify true bus phase connections by utilizing Carson's equation [1]}, which is employed for deriving the primitive phase impedances of different lines.
